Reduce the amount of metadata SharedMergeTree stores

Why it matters

This feature allows users to reduce the volume of metadata stored in Keeper by SharedMergeTree. It addresses the problem of excessive metadata storage per replica, which can improve Keeper's performance and scalability in distributed environments.

How to use it

To enable this feature, set the setting shared_merge_tree_create_per_replica_metadata_nodes to 0 (false) in your ClickHouse configuration or session settings. This will disable the creation of per-replica metadata nodes in Keeper for SharedMergeTree tables.